522 CYPERACE^E. (SEDGE FAMILY.) 



long, dark brown ; scales smooth, rigid, rounded ; nut obovate, acute, slightly 

 furrowed and pitted. (Scirpus castaneus, Michx. S. ferrugineus, Ell.) Salt 

 marshes, Florida, and northward. Aug. - Oct. 



Var. puberula. (Scirpns puberulus, Michx.) Culms single, slender (1- 

 2 high) ; leaves filiform, involute, and, like the spikes, densely pubescent and 

 somewhat hoary ; nut round-obovate, obtuse. Low pine barrens. 



2. P. laxa, Vahl. Annual; culms (6' -18' high) slender, and, like the 

 narrowly linear leaves, often pubescent ; umbel mostly simple ; involucre 2-4- 

 leaved ; spikes oblong-ovate ; scales orbicular, mucronate ; nut obovate, strongly 

 furrowed and pitted, warty on the edges. (Scirpus sulcatus, Ell.) Low 

 grounds, in fields and waste places, Florida to North Carolina. Aug. and Sept. 

 Umbel occasionally reduced to a single spike. 



* * Spikes clustered, sessile. 



3. F. COngesta, Torr. Annual; culms densely tufted (3' -6' high), bris- 

 tle-like, like the rough leaves ; spikes 5 - 10 in a terminal cluster, oblong or cylin- 

 drical, pale, or at length yellowish brown ; involucre 4-leaved, erect-spreading, 

 longer than the culm ; scales lanceolate, tapering into a slender spreading point ; 

 nut oblong-obovate, crossed with faint lines. Banks of the Apalachicola River, 

 Florida, and westward. Aug. and Sept. Spikes 2" - 3" long. 



11. TRICHELOSTYLIS, Lestib. 



Spikes terete, many-flowered. Scales imbricated in few (4-8) rows. Peri- 

 anth none. Style 3-cleft, tumid at the base, deciduous. Nut 3-angled. Culms 

 jointless, leafy at the base. Spikes umbelled. 



1. T. autumnalis. Culms slender, flat, 2-edged, 6' -12' high, tufted ; 

 involucre 2-leaved, mostly shorter than the simple compound or decompound 

 umbel ; spikes linear-lanceolate ; scales ovate-lanceolate, mucronate, imbricated 

 in 4 rows ; stamens 2 ; nut white, obovate, obtuse, often warty. ( Scirpus autum- 

 nalis, L.) Low grounds, Florida to Mississippi, and northward, very common. 

 July - Oct. 



12. ISOLEPIS, R. Brown. 



Spikes few - many-flowered. Scales imbricated in few - several rows. Peri- 

 anth none. Style 3-cleft, the tumid base persistent at the apex of the 3-angled 

 nut. All annuals (in our species), with filiform or bristle-form culms and 

 leaves. Spikes umbelled or clustered. Leaves radical. 



* Spikes umbelled. ( Scales j>,il^ce>,t.) 



1. I. capillaris, R. & S. Culm (4' -6' high) smooth, furrowed, and, like 

 the rough-edged leaves, bristle-like ; spikes 3 - 4, in a simple umbel, oblong, 6-8- 

 flowered ; scales oblong, obtuse, strongly keeled, brown on the sides, imbricated 

 in 4 rows ; nut obovate, obtuse, nearly equal-sided, transversely wrinkled ; sta- 

 mens 2. (Scirpns capillaris, L.) Moist sandy places, Florida, and northward. 

 June - Sept. Sheaths of the leaves bearded at the throat. Involucre 2-3- 

 leaved, scarcely longer than the umbel. 



